This invention relates to herbicidal compositions and methods of use. In particular, this invention relates to herbicidal compositions comprising an herbicidally active thiolcarbamate in combination with certain organophosphate compounds, the latter serving to prolong the effectiveness of a single application of the thiolcarbamate in controlling undesired plant growth.
Thiolcarbamates are well known in the agricultural art as herbicides useful for weed control in crops such as corn, potatoes, beans, beets, spinach, tobacco, tomatoes, alfalfa, rice and others. Thiolcarbamates are primarily used in pre-emergence application, and are particularly effective when incorporated into the soil prior to the planting of the crop. The concentration of the thiolcarbamate in the soil is greatest immediately after application of the compound. How long thereafter the initial concentration is retained depends in large part on the particular soil used. The rate at which the thiolcarbamate concentration declines following its application varies from one type of soil to the next. This is evident both in the observable extent of weed control and in the detectable presence of undegraded thiolcarbamate remaining in the soil after considerable time has elapsed.
It is therefore an object of this invention to increase the soil persistence of thiolcarbamate herbicides and thus improve their herbicidal effectiveness.